Nebulas are clouds of dust and gas particles gathered from the universe. There are three different types of nebulae, planetary, solar, and diffuse nebulas. Included in diffuse nebulas are emission, reflecting, and dark nebulae. Emission nebulas put off light from the young stars located in them. They are usually the most colorful of nebula, the colors vary by the different gases and dust that the nebulae are composed of. Also, reflection nebulas reflect the light from stars in and around the nebulae. Unlike the other nebulae, dark nebulae blocks light from objects all around it. But like all other nebulae it doesn’t produce light of its own. Dark nebulae is one of the many reasons we cannot see far into our galaxy, because there are an abundant amount of clusters of dust and gas, or nebulae. Planetary usually have a circular shape due to their process of creation.
The Orion Nebula, an emission nebula is courtesy of http://www.robgendlerastropics.com/Nebulas.html
Formation and Composition
There are many different ways that nebulas come to be in space. Many form from gas giving way in the ISM or interstellar medium. The ultraviolet radiation from the massive stars formed when the gas gives in the ISM ionizes the gas left, creating plasma, which also makes it possible to see at optical wavelengths. An example of the left over product would be the Pelican Nebula. Also, some nebula form after a supernova, a very large and short lived star explodes. The remnants of the exploded supernova are usually ionized, creating nebulae. Not only do these remnants ionize but also may create a compact object, like the one in the center of a nebulae made through this process, the Crab Nebula. The final other process to forming a nebulae is to be formed as a planetary nebulae. The Sun, at the center of our universe, is in the last stage of a low mass stars life cycle, which is also known as a planetary nebulae. Once a star has lost a considerable amount of material, the ultraviolet radiation it naturally admits ionizes the nebulae that is left over, all the while the temperature increases. The whole process is heading towards equilibrium. Like the varying processes, there are varying sizes of nebulae, due to the original abundance of the cloud of gas.
Observing
Shortly following the telescope being invented, one of the most famous and favored nebulas, the Orion Nebula, was discovered by Nicolas Claude Fabri de Peiresc. He was a French scholar and a naturalist, like Christian Huygens who was Dutch and a scientist. This Dutch scholar was the first to describe the inner region of the Orion nebula, also determining that it is a compact quadruple system. Many nebulae were accidentally discovered in the 18th century by comet seekers. Many of these comet researchers gathered data to make catalogs to prevent from comet confusion. Frenchmen Charles Messier was known for his catalog published in 1781 with 35 galaxies and 11 actual nebulas.
During middle and early 19th century, English astronomers William Herschel and his son John were the greatest observers of their time. Herschel and his sister Caroline gathered three catalogues with about 2,500 nebulous objects, clusters, and galaxies. His son later added 1,700 other objects to the catalogues that were visible from the Cap observatory in London, where there are 500 more objects visible. Herschels catalog was the basis for the great New General Catalogue of J.L. Dreyer, which was published in 1888. In this catalog there are locations and brief descriptions of 7,840 galaxies, clusters, and nebulae. An advancement to photography and spectroscopy, which are both used to observe nebulae, is the advent of photography, which provides record of faint details not seen by the naked eye. This also brought about a revolution in the comprehension of nebulae. These early detailed photos helped to extend to unexpected distances for observers. A lot of nebulae observing is done by studying the objects spectrum. The spectrum is the resolution of its lights into different wavelengths, which helps to indicate whether the object has unresolved stars or glowing gas. Stars radiate at all the varying wavelengths, usually with dark absorption lines superimposed. On the other hand, when heated, transparent gas clouds give off only emission lines at particular wavelengths.
Dark nebula-The Horsehead nebula is courtesy of http://www.sidewalk-astronomy-club.com/img/horsehead-nebula.jpg
Other Facts
While the motions of gas in all kinds of nebulas are complex and spastic, not all are just motions. When the motions in nebulae are chaotic, they are called turbulence. When low viscosity in flowing fluids happens, so does this well-known phenomena. Turbulence has significant but mostly not understood effects on the energy balance and pressure support in the nebula it is in. This phenomena is observed by the means of the widths of absorption or emission lines in a nebular spectrum. Also observations show that turbulence represents bulled motions, independent of the mass of the atoms of the nebulae. Nebulae appear in all kinds of different colors, shapes, and structures. The way we are able to view nebulae in all theses colors and in general is due to spectroscopy and advancements in photography of the universe. Spectroscopy is the study of the spectrum of light through which the light from the nebulae passes through. Different colors of light pass through a prism at different times, creating a spectrum. Nebulae were technically the first thing is the universe, considering they are just a composite of interstellar dust and gases. While they are just dust and gases, they are believed to be what all planets and star root from. Also, the sun was believed to be composed in a solar nebula, which would have been the ultimate and first creation of the universe.
Table of Contents
Nebulas
Nebulas are clouds of dust and gas particles gathered from the universe. There are three different types of nebulae, planetary, solar, and diffuse nebulas. Included in diffuse nebulas are emission, reflecting, and dark nebulae. Emission nebulas put off light from the young stars located in them. They are usually the most colorful of nebula, the colors vary by the different gases and dust that the nebulae are composed of. Also, reflection nebulas reflect the light from stars in and around the nebulae. Unlike the other nebulae, dark nebulae blocks light from objects all around it. But like all other nebulae it doesn’t produce light of its own. Dark nebulae is one of the many reasons we cannot see far into our galaxy, because there are an abundant amount of clusters of dust and gas, or nebulae. Planetary usually have a circular shape due to their process of creation.
Formation and Composition
There are many different ways that nebulas come to be in space. Many form from gas giving way in the ISM or interstellar medium. The ultraviolet radiation from the massive stars formed when the gas gives in the ISM ionizes the gas left, creating plasma, which also makes it possible to see at optical wavelengths. An example of the left over product would be the Pelican Nebula. Also, some nebula form after a supernova, a very large and short lived star explodes. The remnants of the exploded supernova are usually ionized, creating nebulae. Not only do these remnants ionize but also may create a compact object, like the one in the center of a nebulae made through this process, the Crab Nebula. The final other process to forming a nebulae is to be formed as a planetary nebulae. The Sun, at the center of our universe, is in the last stage of a low mass stars life cycle, which is also known as a planetary nebulae. Once a star has lost a considerable amount of material, the ultraviolet radiation it naturally admits ionizes the nebulae that is left over, all the while the temperature increases. The whole process is heading towards equilibrium. Like the varying processes, there are varying sizes of nebulae, due to the original abundance of the cloud of gas.
Observing
Shortly following the telescope being invented, one of the most famous and favored nebulas, the Orion Nebula, was discovered by Nicolas Claude Fabri de Peiresc. He was a French scholar and a naturalist, like Christian Huygens who was Dutch and a scientist. This Dutch scholar was the first to describe the inner region of the Orion nebula, also determining that it is a compact quadruple system. Many nebulae were accidentally discovered in the 18th century by comet seekers. Many of these comet researchers gathered data to make catalogs to prevent from comet confusion. Frenchmen Charles Messier was known for his catalog published in 1781 with 35 galaxies and 11 actual nebulas.
During middle and early 19th century, English astronomers William Herschel and his son John were the greatest observers of their time. Herschel and his sister Caroline gathered three catalogues with about 2,500 nebulous objects, clusters, and galaxies. His son later added 1,700 other objects to the catalogues that were visible from the Cap observatory in London, where there are 500 more objects visible. Herschels catalog was the basis for the great New General Catalogue of J.L. Dreyer, which was published in 1888. In this catalog there are locations and brief descriptions of 7,840 galaxies, clusters, and nebulae. An advancement to photography and spectroscopy, which are both used to observe nebulae, is the advent of photography, which provides record of faint details not seen by the naked eye. This also brought about a revolution in the comprehension of nebulae. These early detailed photos helped to extend to unexpected distances for observers. A lot of nebulae observing is done by studying the objects spectrum. The spectrum is the resolution of its lights into different wavelengths, which helps to indicate whether the object has unresolved stars or glowing gas. Stars radiate at all the varying wavelengths, usually with dark absorption lines superimposed. On the other hand, when heated, transparent gas clouds give off only emission lines at particular wavelengths.
Other Facts
While the motions of gas in all kinds of nebulas are complex and spastic, not all are just motions. When the motions in nebulae are chaotic, they are called turbulence. When low viscosity in flowing fluids happens, so does this well-known phenomena. Turbulence has significant but mostly not understood effects on the energy balance and pressure support in the nebula it is in. This phenomena is observed by the means of the widths of absorption or emission lines in a nebular spectrum. Also observations show that turbulence represents bulled motions, independent of the mass of the atoms of the nebulae. Nebulae appear in all kinds of different colors, shapes, and structures. The way we are able to view nebulae in all theses colors and in general is due to spectroscopy and advancements in photography of the universe. Spectroscopy is the study of the spectrum of light through which the light from the nebulae passes through. Different colors of light pass through a prism at different times, creating a spectrum. Nebulae were technically the first thing is the universe, considering they are just a composite of interstellar dust and gases. While they are just dust and gases, they are believed to be what all planets and star root from. Also, the sun was believed to be composed in a solar nebula, which would have been the ultimate and first creation of the universe.
References
¹ Nebulas (astronomy) from Britannica Online Encyclopedia
² Nebulas from NASA
³ Nebulae and Birth from Journey through the Galaxy
⁴The Chemical Compostion of Stars